This application is related to improving the bioavailability of carotenoids as provided in formulated mixtures to animals. The invention provides both a specific composition and a method of manufacture for improved delivery of carotenoids.
This invention relates to a carotenoid composition and methods for its manufacture and use. In one aspect, the invention relates to carotenoids, synthetic or naturally produced by a single-celled organism, and phospholipids containing highly unsaturated fatty acids. In another aspect, the invention relates to methods of increasing carotenoid stability during feed processing and improving bioavailability in the gastrointestinal (GI) tract of coldwater species. In yet another aspect, the invention relates to using products made from these carotenoid compositions as a dietary supplement in various animal feeds.
The carotenoids, as a class of compounds, are classified into two main groups: carotenes and xanthophylls. In contrast to carotenes, which are pure polyene hydrocarbons, such as beta-carotene or lycopene, xanthophylls contain oxygen functional groups, such as hydroxyls, epoxy and/or oxo groups. Typical representatives of the xanthophyll group are astaxanthin, canthaxanthin and zeaxanthin.
A distinct red color is of prime importance to customer acceptance of a subset of food products, particularly aquatic food animals such as salmon, trout, shrimp, lobster and many other marine animals (Hinostroza, Huberman et al. 1997; Bjerkeng and Berge 2000). The oxygenated carotenoids (xanthophylls) are responsible for the red color of these aquatic animals. These xanthophylls are also useful for adding pigmentation to the flesh and products of other animals, and to other foodstuffs, for example poultry and eggs, various dairy products, snack foods, and the like.
Astaxanthin is the most abundant carotenoid present in the aquatic world (Shahidi, Metusalach et al. 1998). Aquatic animals, like terrestrial animals, generally cannot synthesize astaxanthin or any other carotenoid, although many of these animals accumulate carotenoid compounds that are present in their diets. Some of these animals, such as crustaceans, can interconvert some carotenes to xanthophylls, of which astaxanthin is the predominant compound formed. However, aquatic fish accumulate dietary astaxanthin even though these fish cannot convert any other carotenoid compound to astaxanthin. Therefore, the astaxanthin present in aquatic fish, and in products produced from these fish, must be derived directly from dietary sources.
Currently, synthetic astaxanthin is added to feeds of aquacultured salmonids to provide a source of this carotenoid (Bell, McEvoy et al. 1998). In some cases, synthetic canthaxanthin (another xanthophyll that is very closely related to astaxanthin) is used in place of astaxanthin in feeds for salmonids, but this compound does not function as well in these fishes as the naturally predominant astaxanthin (Bell, McEvoy et al. 1998).
Natural sources of dietary astaxanthin, including krill, crawfish, crustacean processing by-products, bacteria, yeast, algae, and higher plants are in great demand by aquacultural industries. However, these natural sources tend to be too expensive and of limited availability and reliability to be commercially viable. Lycopene is an alternative natural carotenoid that might meet the cost criterion for inclusion in feeds (Clark, Yao et al. 2000). It is in a class of carotenoids that characteristically gives color to many vegetables.
Carotenoids are easily isomerized by heat, acid or light. Once isomerized, they lose their biological antioxidant properties (Fennema 1996). The high demands placed on xanthophyll-containing formulations with respect to coloring action and bioavailability can thus not always be met because of these problems (Yeum and Russell 2002). Indeed, various processes and a number of combined emulsifying/spray-drying processes (see patents DE-A-12 11 911 or in EP-A-0 410 236) have been proposed to improve the color yields and to increase the absorbability or bioavailability carotenoids.
One specific problem which has not yet been addressed is related to the low body temperature of salmonid fishes, which is equal to the temperature of the water in which they inhabit, generally 0 to 14° C. Natural astaxanthin, especially those in Phaffia yeasts, are concentrated in oil droplets that contain about 13% palmitic acid (16:0) with a melting point of 64° C., and about 32% oleic acid (18:1n9) with a melting point of 16° C. (Deuel 1951). Because of these high melting point fatty acids, the astaxanthin containing oil droplets solidify near 10° C. This makes it difficult for the fish to incorporate the astaxanthin from the solidified oil droplet at water temperatures below 10° C. This is especially problematic for coldwater fish.